Teaching Kindergarten students how to write begins with learning letter sounds. I encourage students to say the words slowly and eventually they learn how to clap out the sounds in a word to spell and how to break a word into syllables to spell. They learn that books have a central theme and create "label books", where they label the pictures in their book.
Once they are comfortable spelling simple words and have learned some basic sight words, they learn how to write "pattern sentences". These books have a sentence pattern. (Ex. I see the ___.) Once again, their books should have a theme.
After pattern sentence books, students learn how to write a personal narrative, informational text, and opinion writing. By the end of Kindergarten, most students are able to write 5-8 sentences without support.